Denitrifying woodchip bioreactors (DBRs) are an established nitrate mitigation technology, but uncertainty remains on their viability for phosphorus (P) removal due to inconsistent source-sink behaviour in field trials. We investigated whether iron (Fe) redox cycling could be the missing link needed to explain P dynamics in these systems. A pilot-scale DBR (Aotearoa New Zealand) was monitored for the first two drainage seasons (2017-2018), with supplemental in-field measurements of reduced solutes (Fe, HS/HS) and their conjugate oxidised species (Fe/SO) made in 2021 to constrain within-reactor redox gradients. Consistent with thermodynamics, the dissolution of Fe to Fe within the DBR sequentially followed O, NO and MnO reduction, but occurred before SO reduction. Monitoring of inlet and outlet chemistry revealed tight coupling between Fe and P (inlet R 0.94, outlet R 0.85), but distinct dynamics between drainage seasons. In season one, outlet P exceeded inlet P (net P source), and coincided with elevated outlet Fe, but at ⁓50 % lower P concentrations relative to inlet Fe:P ratios. In season 2 the reactor became a net P sink, coinciding with declining outlet Fe concentrations (indicating exhaustion of Fe hydroxides and associated P). In order to characterize P removal under varying source dynamics (i.e. inflows vs in-situ P releases), we used the inlet Fe vs P relationship to estimate P binding to colloidal Fe (hydr)oxide surfaces under oxic conditions, and the outlet Fe concentration to estimate in-situ P releases associated with Fe (hydr)oxide reduction. Inferred P-removal rates were highest early in season 1 (k = 0.60 g P m d; 75-100 % removal), declining significantly thereafter (k = 0.01 ± 0.02 g P m d; ca. 3-67 % removal). These calculations suggest that microbiological P removal in DBRs can occur at comparable magnitudes to nitrate removal by denitrification, depending mainly on P availability and hydraulic retention efficiency.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1016/j.scitotenv.2024.170478 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
A holistic study on the effects of a rural flood detention basin: Flood peaks, water quality and grass growth.
J Environ Manage
December 2024
School of Biological, Earth and Environmental Sciences, University College Cork, Cork, Ireland; Environmental Research Institute, Ellen Hutchins Building, University College Cork, Cork, Ireland.
Nature-based Solutions (NbS) are widely advocated to have multiple benefits, including in flood risk reduction, water quality improvement and ecosystem health. There are, however, few empirical studies quantifying such multi-functionality. Given the ongoing pressures of flooding and poor water quality within Europe, there is an urgent need for empirical evidence to assess the potential for NbS features to address these issues.
View Article and Find Full Text PDFNovel Stepped Combined Constructed Wetland For Surface Water Removal: Enhancing the Performance and Responses of Microbial Communities.
ACS Omega
December 2024
East China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, 300 Jungong Road, Shanghai 200090, China.
Micro-polluted surface waters (MPSWs) draw increased concern for environmental protection. However, traditional treatment methods such as activated sludge, ozone activated carbon, and membrane filtration suffer from high cost and susceptibility to secondary pollution and are rarely used to address MPSWs. Herein, a new stepped combined constructed wetland planted with without additional inputs was developed.
View Article and Find Full Text PDFReduce the application of phosphorus fertilizer in peanut fields and improve its efficiency by using iron modified biochar to adsorb phosphorus recovery products.
Front Plant Sci
December 2024
Institute of Soil and Fertilizer and Agricultural Sparing Water, Xinjiang Academy of Agricultural Science, Urumqi, China.
Introduction: To address the scarcity of agricultural phosphorus (P) fertilizers and reduce phosphorus accumulation in wastewater, this study employed iron-modified biochar (Fe-B) to adsorb phosphorus from water. The phosphorus-loaded iron-modified biochar (Fe-BP) was subsequently applied to peanut fields. Batch experiments were conducted to determine the optimal adsorption parameters and mechanism of Fe-B for phosphate ions (PO ).
View Article and Find Full Text PDFPyrite in recirculating stacking hybrid constructed wetland: Electron transfer for nitrate reduction and phosphorus immobilization.
J Environ Manage
December 2024
Department of Ecology, Engineering Research Center for Tropical and Subtropical Aquatic Ecological Engineering, Ministry of Education, Jinan University, Guangzhou, 510632, PR China. Electronic address:
Pyrite is considered as an effective and environmentally friendly substrate in constructed wetlands (CW) for wastewater treatment, but its application in recirculation stacking hybrid constructed wetlands (RSHCW) has been scarcely studied. This study uses varying amounts of pyrite as the substrate in RSHCW, leveraging the recirculation of wastewater to alter microenvironments such as dissolved oxygen (DO) and pH, to explore the potential mechanisms of nitrogen (N) and phosphorus (P) removal in pyrite-based RSHCW. The results show that as the proportion of pyrite increases, the removal rate of total phosphorus (TP) in the effluent also increases (25%→58%), significantly enhancing the deposition of iron-bound phosphorus (Fe-P) on the substrate, thereby turning CW into a P reservoir.
View Article and Find Full Text PDFStudy of modified ion exchange resins for phosphorus removal from glyphosate by-product salt.
Environ Technol
December 2024
School of Materials Science and Engineering, Yancheng Institute of Technology, Yancheng, People's Republic of China.
In order to achieve the goal of phosphate removal from glyphosate by-product salts, zirconium and zinc ions were successfully loaded onto D202 resin by co-precipitation modification method in this study, and their effectiveness in phosphate removal was evaluated under various conditions. The results of static adsorption experiments showed that the Zr/Zn@D202 resin effectively reduced the phosphate concentration in the glyphosate by-product salts from 10 mg/L to less than 0.1 mg/L, which met the national level emission standard ( < 0.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!